Dynamics of the Oral Microbiome During Initial Military Training at Fort Benning, Georgia

Kristina K Zudock; Robert Player; Amanda Ernlund; Collin M Timm; Caroline E English; Michael W Ellis; David R Tribble; D Scott Merrell; Jason W Bennett; Eugene V Millar

doi:10.1093/milmed/usad488

Dynamics of the Oral Microbiome During Initial Military Training at Fort Benning, Georgia

Mil Med. 2024 Jan 2:usad488. doi: 10.1093/milmed/usad488. Online ahead of print.

Authors

Kristina K Zudock¹, Robert Player², Amanda Ernlund¹, Collin M Timm², Caroline E English^{3

4}, Michael W Ellis⁵, David R Tribble³, D Scott Merrell⁶, Jason W Bennett^{7

8}, Eugene V Millar^{3

4}

Affiliations

¹ Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
² Asymmetric Operations Sector, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
³ Infectious Disease Clinical Research Program, Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
⁴ Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, USA.
⁵ Division of Infectious Diseases, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA.
⁶ Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
⁷ Multidrug-Resistant Organism Repository and Surveillance Network, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
⁸ Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.

PMID: 38243767
DOI: 10.1093/milmed/usad488

Abstract

Introduction: Military trainees are at increased risk for infectious disease outbreaks because of the unique circumstances of the training environment (e.g., close proximity areas and physiologic/psychologic stress). Standard medical countermeasures in military training settings include routine immunization (e.g., influenza and adenovirus) as well as chemoprophylaxis [e.g., benzathine penicillin G (Bicillin) for the prevention of group A streptococcal disease] for pathogens associated with outbreaks in these settings. In a population of U.S. Army Infantry trainees, we evaluated changes in the oral microbiome during a 14-week military training cycle.

Materials and methods: Trainees were enrolled in an observational cohort study in 2015-2016. In 2015, Bicillin was administered to trainees to ameliorate the risk of group A Streptococcus outbreaks, whereas in 2016, trainees did not receive a Bicillin inoculation. Oropharyngeal swabs were collected from participants at days 0, 7, 14, 28, 56, and 90 of training. Swabs were collected, flash frozen, and stored. DNA was extracted from swabs, and amplicon sequencing of the 16s rRNA gene was performed. Microbiome dynamics were evaluated using the QIIME 2 workflow along with DADA2, SINA with SILVA, and an additional processing in R.

Results: We observed that microbiome samples from the baseline (day 0) visit were distinct from one another, whereas samples collected on day 14 exhibited significant microbiome convergence. Day 14 convergence was coincident with an increase in DNA sequences associated with Streptococcus, though there was not a significant difference between Streptococcus abundance over time between 2015 and 2016 (P = .07), suggesting that Bicillin prophylaxis did not significantly impact overall Streptococcus abundance.

Conclusions: The temporary convergence of microbiomes is coincident with a rise in communicable infections in this population. The dynamic response of microbiomes during initial military training supports similar observations in the literature of transient convergence of the human microbiome under cohabitation in the time frame including in this experiment. This population and the associated longitudinal studies allow for controlled studies of human microbiome under diverse conditions.

Abstract

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